In hydrocarbon production chemicals are introduced into a well through a capillary tube for mitigating problems, such as scaling, corrosion, or the deposition of organic products. Chemicals are also introduced in this manner to treat well fluids, reduce viscosity, and/or demulsify.
In prior art downhole chemical injection methods using a single capillary tube, the injected chemicals are not widely dispersed in the radial dimension, resulting in limited mixing of the chemicals and well fluids. This limited mixing can result in chemicals channeling on one side of an electrical submersible pump (“ESP”) located downhole. Such channeling leaves a side or portion of the ESP untreated. Additionally, capillary tubes used with prior art downhole chemical injection devices have been subject to plugging, resulting in a lack of chemical dispersion downhole to protect the ESP.
Another prior art chemical injection method involves injecting chemicals from the well surface into the well annulus. This method involves the chemicals flowing downward as a countercurrent to the gases that are liberated at the pump separator. In this method, the chemicals flow downhole to mix with production fluids and enter the intake or suction of the ESP. Once the mixture of production fluids and chemicals reach the ESP intake, they are discharged from the ESP, rather than flowing down past the ESP motor. Thus, components below the ESP intake, such as the motor, do not receive the intended treatment benefit of the injected chemicals. Downhole motors are especially susceptible to corrosion due to their high operating temperatures.
One or more embodiments of the invention described herein provide improved dispersion of fluids injected downhole and protection of the capillary tube against plugging, for various forms of oil production systems.